Process and device for the manufacture of polygonal tubes

ABSTRACT

This invention concerns a device for the manufacture of polygonal tubes, with a base frame ( 2 ) and an upright assembly wall ( 10 ) that is equipped with a rotating mandrel ( 7 ) having a polygonal cross-section and a drive system ( 6 ); a corrugated strip of foil ( 60 ) fed by feed rolls ( 29 ) is wound onto this mandrel; on both edges, the strip of foil ( 60 ) has a pre-formed fold; during the winding process, adjacent edges with such pre-formed folds can be inserted in each other and closed to form a fold; in the assembly wall ( 10 ), shafts ( 16 ) that are concentric to the axis of rotation of the mandrel ( 7 ) carry arms ( 20 ) with rolling tools ( 30 ) directed at the mandrel ( 7 ).  
     In the device proposed by the invention, at least one shaping roll ( 42 ) is provided that is located outside the mandrel ( 7 ) in axial direction of the tube to be manufactured.

[0001] This invention concerns a device for the manufacture of polygonal tubes, with a base frame and an upright assembly wall that is equipped with a rotating mandrel having a polygonal cross-section and a drive system; a corrugated strip of foil fed by feed rolls is wound onto this mandrel; on both edges, the strip of foil has a pre-formed fold; during the winding process, adjacent edges with such preformed folds can be inserted into each other and closed to form a fold; in the assembly wall, shafts that are concentric to the axis of rotation of the mandrel carry arms with rolling tools directed at the mandrel.

[0002] In addition, the invention concerns a process for manufacturing polygonal hollow sections from a corrugated web of thin material that is wound helically, and with underlapping of the edges for the purpose of forming a fold, onto a polygonal mandrel under the pressure of pressure tools that are movable supported, with the ability to move in an approximately radial direction relative to the mandrel on swiveling arms, pressing the web of material against the outer surface of the mandrel; on both edges, the web of material has a preformed fold that is closed during the winding process by means of at least one shaping roll;

[0003] and also a hollow section made from a web of corrugated thin material that was wound helically, and with overlapping of the edges for the purpose of forming a fold, onto a polygonal mandrel.

[0004] A process and a device for the manufacture of hollow sections are known from DE 19610425. There, it was proposed to develop a manufacturing device for tubes in such a way that shafts with arms are supported concentrically to the axis of rotation of the mandrel in the assembly wall; their free ends carry the rolling tools directed at the mandrel, and the arms are bow-shaped, with a built-in lead relative to the rotation direction of the mandrel. Only axial folds for joining the web of material can be manufactured with this device.

[0005] DE 3404139 describes a process and a device for manufacturing hollow sections from a corrugated web of thin material. This device includes pressure devices supported in the base plate that can be moved in radial direction relative to the tube to be formed by means of a pneumatic cylinder. A disadvantage of this design of the device is that, especially with hollow sections with sharp edges, such as rectangular hollow sections, large forces are exerted on the forming tools, which are therefore subject to damage.

[0006] DE 2829283 introduced a process for manufacturing helically wound tubes that are folded along the entire longtudinal edges of the strips. The fold is radial so that the corrugation of the tube is uninterrupted. This allows such pipes to be pushed closer together and to be bent at smaller radii than is possible with axial folds. The process is used for the manufacture of hollow sections with a round cross-section.

[0007] Until now, the devices and processes representing the state of technology have not allowed the manufacture of hollow sections with a polygonal cross-section, for example a rectangular or a square cross-section, where the connecting fold is located radially. With polygonal tubes, the area around the edges requires a large deformation of the sectional material that the devices and processes representing the state of technology were unable to produce.

[0008] This invention addressed the problem of providing a device and a process for the manufacture of polygonal sections from a corrugated web of thin material that was wound helically, and with overlapping of the edges for the purpose of forming a fold, onto a polygonal mandrel, where the fold runs approximately radially to the center axis of the hollow section.

[0009] This problem is solved by a device according to patent claim 1 and by a process according to patent claim 13, as well as by a hollow section according to patent claim 14.

[0010] The device proposed by the invention provides for at least one shaping roll located outside the mandrel in the axial direction relative to the tube to be manufactured. This shaping roll, of which at least one is required, ensures the sufficient deformation of the material to be folded even in the edge area of the polygonal section.

[0011] In a preferred design variant of the device proposed by the invention, the device includes a first and second shaping roll, with the first shaping roll placed on the outside of the tube and the second shaping roll placed on the inside of the tube. The combined effect of the two shaping rolls provides for a more precise formation of the fold, and a greater deformation of the material to be folded.

[0012] A preferred design variant further provides for the surfaces of the first and the second shaping rolls to approximately face each other. In this way, the shaping rolls can participate simultaneously in the deformation of the material for the purpose of creating the fold

[0013] A preferred design variant further provides for the first and the second shaping roll to each consist of individual disks, with the disks spaced axially relative to the axis of rotation of the shaping roll. In this way, due to a lard contact areas the shaping rolls ensure the reliable guidance of the section in the area of the fold to be created without damaging the corrugated surface.

[0014] A preferred design variant further provides for the first and the second shaping roll to mesh so that some disks of both shaping rolls partially overlap in axial direction. This design allows a greater deformation of the sectional material in the area of the fold to be created.

[0015] In addition, the device may be designed in such way that the first and/or the second shaping roll are located on at least one rotating arm. This has the effect that the radial distance of the shaping rolls from the center axis of the hollow section can be changed easily.

[0016] In a preferred design variant, the first shaping roll is placed on a first arm, and the second roll is placed on a second arm. This makes the shaping rolls independent of, and adjustable relative to each other.

[0017] Preferably, the first arm and the second arm are coupled kinematically. In this way, the arms, and therefore the shaping rolls, can be moved together as determined by the kinematics of the coupling.

[0018] A preferred design variant provides for the shaping rolls to move axially with reference to the circumferential line of the mandrel. In this way, the creation of the fold becomes independent of the geometry of the mandrel, and, therefore, the geometry of the hollow section.

[0019] The first and the second arm may be coupled hydraulically, pneumatically, or by means of a spring. This allows for couplings of varying rigidity.

[0020] A preferred design variant provides for at least one shaping roll to engage the foil strip in such way that, during or after the closing of the fold, the fold is located in the radial direction of the tube. The closing of the fold can be done in several steps with the help of different rolls, with a last step ensuring a radial alignment of the fold.

[0021] The process for the manufacture of polygonal hollow sections from a corrugated web of thin material, as proposed by the invention, provides for the fold to be shaped in such way that it is essentially radial relative to the center axis of the tube. Likewise, with the hollow section, the fold is approximately radial relative to the center axis of the hollow section. Such a hollow section can be stretched or compressed by a factor of two to three. Due to the high stretching and compression characteristics, the hollow section can be bent at tighter radii than polygonal hollow sections produced with the current state of technology.

[0022] Below, a design variant of the invention is described in detail, with reference to the enclosed drawing.

[0023]FIG. 1 shows a front view of the device;

[0024]FIG. 2 shows a sectional view corresponding to II-II in FIG. 1;

[0025]FIG. 3 shows a partial view of the shaping rolls.

[0026]FIG. 1 provides an overview of a winding device 1 with attached roll pre-former 5. The foil strip, not shown here, is pulled off a storage spool, also not shown here, and it then runs through the feeder 4 into a roll pre-former 5 where it is corrugated by means of the rolls 5.1 and receives the lateral pre-folds. The pre-fold on one of the strip edges is shaped so that it can be placed into the pre-fold of the other strip edge, and can be pressed together to form a closed fold The rolls 5.1 of the roll pre-former 5 have their own drive system 6. The rolls 5.1 represent a roll forming line supported by the roll-forming frame 3, from which the foil strip corrugated in this manner is fed into the actual winding device 1. The foil strip prepared in this manner runs across the feed rolls 29 to the mandrel 7, and is wound on this mandrel in spiral fashion so that the pitch corresponds exactly to the strip width without the pre-fold. In order to achieve this pitch, the roll pre-former 5 with its roll forming line consisting of the rolls 5.1 is placed at an angle (that corresponds to this pitch) to the direction of the axis of the mandrel. For this purpose, the frame is equipped with rollers 3.1, and is connected with the base frame 2 of the winding device via a sp ace maintaining bar 3.2.

[0027] In order to apply the corrugated foil strip to the surface of the mandrel 7, thereby replicating its polygonal shape, rolling tools 30 are provided that are located at the free ends of arms 20. By means of a pivot shaft 23, as shown in FIG. 2, the arms 20 are supported by the beatings 15 in the assembly wall 10 of the base frame 2 of the device 1, and means are provided that push the arms 20 with the rolling tools 30 at their free ends towards the mandrel 7. These means supply the force for pressing the corrugated foil strip 60 against the surface of the mandrel 7. It advantageous if a second bearing is provided; here, this is accomplished by a ring-shaped arm carrier 11 that is firmly connected with the assembly wall 10, leaving a space in between that accepts the arm 20; the ring shape permits the wound tube to exit without hindrance. In the area of the feed rolls 29, the arm carrier 11 is interrupted by a feed opening 14 to allow the feeding of the corrugated foil strip. In the area of the arm carrier 11, the pivot shafts 23 of the arms 20 are held in bearings 16 so that pitching moments are suppressed. The design variant shown here has six arms 20 arranged concentrically to the axis of the mandrel 7. The mandrel 7 shown here has a rectangular shape. However, almost any other shape is possible, such as pentagonal, hexagonal, or square shapes. In order to achieve uniform contact pressure, the arms 20 can be pivoted out or pushed back.

[0028]FIG. 2 shows a side view of the winding device corresponding to the section II-II in FIG. 1 of the base frame 2 on which the assembly wall 10 is mounted in fixed position. The drive shaft 7.1 for the mandrel 7 passes through the assembly wall 10 where it is supported in bearing 9 in such a way that the unilateral forces can be absorbed. A drive motor 8 for driving the mandrel 7 is provided, acting on the drive shaft 7.1 of the mandrel 7 via a belt reduction gear 8.1. The arm carrier 11 is located in front of the assembly wall 10, leaving a space in between for the arms 20. By means of the bearings 15 located in the assembly wall 10 and the bearings 16 located in the arm carrier 11,the arms 20 are able to pivot, with the pivot shaft 23 passing through the assembly wall 10. Each of the arms 20 is formed by a box-shaped section that is open on one side and consists of the base strap 21 and two lateral flanges 22. This design, while offering sufficient rigidity, makes for a low weight of the arm that is necessary for operating at high winding speeds, so that a tracking delay due to excessive inertia does not become an issue. In the arms 20, the base strap s 21 are extended and shaped to form eyes 21.1 that accept the pivot shafts 23 that are fly attached to the arms 20. The end of the shaft passes through the assembly wall 10 and is connected, by means of a rocking lever 25, with the head 28 of the piston rod of a pneumatic or hydraulic cylinder 26 whose other end, as a cylinder base, is supported by the assembly wall 10, and therefore by the base frame 2, thus closing the circle of forces. Due to the pitch of the windings it is necessary to stagger each of the arms 20 on the pivot shaft 23 by an appropriate amount relative to the pitch. In the design variant shown here, with its six arms 20, each of the arms is staggered by ⅙ of the pitch. Since the feed rollers 29 in FIG. 1 have a not negligible distance from their corresponding rolling tool 30′ of the corresponding arm 20′, this arm is widened correspondingly. The free ends of the arms 20 carry the rolling tools 30 that press the corrugated foil strip against the surface of the mandrel 7. With each of the rolling tools 30, the actual contact roll 33 is held in a fork 31 that is linked to the free end of the corresponding arm 20 and has the ability to swivel around an axis that is perpendicular to the axis of rotation of the mandrel 7. This permits an adaptation of the contact position of the contact roll 33 to the varying pitches that differ from dimension to dimension of the polygonal mandrel shapes. To produce this swiveling action, a turning gear in the shape of a worm gear 34 is provided that also permits an adjustment of the contact position of the rolls during the winding process.

[0029] During the winding process, the pre-folds of the strip edges are inserted into each other and, in a first step, are pushed together while passing through the various rolling tools 30. The actual fold is produced outside the mandrel 7 by means of a first shaping roll 41 and a second shaping roll 42. The first shaping roll 41 is located on the outside of the hollow section, and the second shaping roll 42 is located inside the hollow section. As shown in FIG. 2, the first shaping roll 41 is rigidly connected with one of the rolling tools 30 by means of a second fork 43. Therefore, the swiveling motion that can be performed by the first shaping roll 41 corresponds essentially to the swiveling motion that can be performed by the rolling tools 30. The second shaping roll 42 rotates on a shaft 44. The shaft 44 forms a moving arm, similar to arm 20. The shaft 44 passes through the mandrel 7 and the tube shaped bearing 9, and is held in a support 45. By means of a coupling rod 46, the support 45 and therefore the second shaping roll 42 are coupled with the second fork 43 and therefore with the first shaping roll 41 so that the first shaping roll 41 and the second shaping roll 42 can be moved in a practically identical manner. REFERENCE LIST 1 Winding Device 2 Base Frame 3 Roll Shaping Frame 3.1 Rolls 3.2 Arm 4 Feed-In 5 Roll Preformer 5.1 Rolls 6 Drive System 7 Mandrel 10 Assembly Wall 11 Arm Carrier 14 Feed Opening 15 Bearing 16 Bearings 20 Arm 21 Base Strip 21.1 Eyelets 22 Lateral Flange 23 Pivot Shaft 25 Swivel Lever 27 Cylinder Base 29 Feed Roll 30 Rolling Tools 31 First Fork 33 Pressure Roll 34 Worm Drive 41 First Shaping Roll 42 Second Shaping Roll 43 Second Fork 44 Shaft 45 Holder 46 Coupling Bar 51 Holder 52 Guide Roll 60 Foil Strip A Axial Fold B Radial Fold

[0030]FIG. 3 illustrates the interaction of the first shaping roll 41 with the second shaping roll 42. The foil strip 60 is wound onto the mandrel 7. FIG. 3 shows a longtudinal section of the foil strip 60, illustrating its profile. The pressure roll 33 is supported jointly with the first shaping roll 41 in a holder 51. The holder 51 includes the first fork 31 for accepting the pressure roll 33 as well as the second fork 43 for accepting the shaping roll 41. Therefore, both rolls are rigidly coupled as regards their axial and radial motion. In addition, the holder 51 contains a guide roll 52.

[0031] In order to produce the finished fold, in a first step, the lateral pre-folds of the foil strip 60 are pressed on top of each other by the combined effect of the pressure roll 33 and the mandrel 7, producing the axial fold A whose cross-section can be seen in FIG. 3. The combined effect of the first shaping roll 41 and the second shaping roll 42 deforms the axial fold 4 along with an additional layer of material to produce the radial fold B. The guide roll 52 ensures the formation of the fold and serves also to move the finished hollow section out of the device. 

1 Device for the manufacture of polygonal tubes, with a base frame (2) and an upright assembly wall (10) that is equipped with a rotating mandrel (7) having a polygonal cross-section and a drive system (6); a corrugated strip of foil (60) fed by feed rolls (29) is wound onto this mandrel; on both edges, the strip of foil (60) has a pre-formed fold; during the winding process, adjacent edges with such pre-formed folds can be inserted in each other and closed to form a fold; in the assembly wall (10), shafts (16) that are concentric to the axis of rotation of the mandrel (7) carry arms (20) with rolling tools (30) directed at the mandrel (7), characterized by the feature that at least one shaping roll (42) is provided that is located outside the mandrel (7) in axial direction of the tube to be manufactured. 2 Device according to claim 1, characterized by the feature that this includes a first shaping roll (41) and a second shaping roll (42), with the first shaping roll (41) located on the outside of the tube, and the second shaping roll (42) located on the inside of the tube. 3 Device according to claim 3, characterized by the feature that the surfaces of the first and second shaping roll (41, 42) approximately face each other. 4 Device according to one of the claims 2 or 3, characterized by the feature that the first and second shaping roll (41, 42) each consists of individual disks, and that the disks are axially spaced with reference to the axis of rotation of the shaping rolls (41,42). 5 Device according to claim 4, characterized by the feature that the first and the second shaping roll (41, 42) mesh with each other in such way that some disks of both shaping rolls partially overlap each other in axial direction. 6 Device according to one of the claims 1-5, characterized by the feature that the first and/or the second shaping roll are mounted on at least one swiveling arm (20, 44). 7 Device according to claim 6, characterized by the feature that the first shaping roll is mounted on a first arm (20) and the second shaping roll is mounted on a second arm (44). 8 Device according to claim 7, characterized by the feature that the first arm (20) and the second arm (44) are coupled kinematically. 9 Device according to one of the claims 2 to 8, characterized by the feature that the first and the second shaping roll (41, 42) can be moved axially with reference to the circumferential line of the mandrel. 10 Device according to one of the claims 8 to 9, characterized by the feature that the first arm (20) and the second arm (44) are coupled hydraulically. 11 Device according to one of the claims 8 to 9, characterized by the feature that the first arm (20) and the second arm (44) are coupled pneumatically. 12 Device according to one of the claims 8 to 9, characterized by the feature that the first arm (20) and the second arm (44) are coupled by means of a spring. 12 Device according to one of the claims 1 to 12, characterized by the feature that at least one of the shaping rolls (41, 42) engages the foil strip (60) in such way that during the closing or after the closing of the fold this fold is located in radial direction of the tube. 13 Process for manufacturing polygonal hollow sections from a corrugated web of thin material (60) that is wound helically, and with overlapping of the edges for the purpose of forming a fold, onto a polygonal mandrel (7) under the pressure of rolling tools (30) that are supported, with the ability to move in an approximately radial direction relative to the mandrel (7) on swiveling arms (20), pressing the web of material (60) against the outer surface of the mandrel (7); on both edges, the web of material (60) has a pre-formed fold that is closed during the winding process by means of at least one shaping roll, characterized by the feature that the fold is formed in such way that it runs essentially radially relative to the center axis of the tube. 14 Hollow section made from a web of corrugated thin material that was wound helically, and with overlapping of the edges for the purpose of forming a fold, onto a polygonal mandrel, characterized by the feature that the fold is approximately radial relative to the center axis of the hollow section. 